1. Field of the Invention
The present invention relates to a 3D image display device and a 3D image display method, and more particularly, to a 3D image display device and a 3D image display method capable of improving image forming quality of a 3D image.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagram showing a 3D image display device of the prior art. As shown in FIG. 1, the 3D image display device 100 of the prior art comprises an image projection unit 110, a scattering element 120, and an optical element 130. The image projection unit 110 is configured to project a plurality of sub-images I1, I2, I3 having different visual angles onto the scattering element 120. A lens array 132 is formed on the optical element 130 for refracting the plurality of sub-images I1, I2, I3 having different visual angles to corresponding display directions respectively, so as to allow a user to see the corresponding sub-images from different viewing angles, such that a 3D image is visually formed to the user.
A distance between the lens array 132 and the scattering element 120 is approximately equal to a focal length of the lens array 132. The focal length of the lens array 132 relates to an overlapping level between the sub-images I1, I2, I3 having different visual angles. When the focal length of the lens array 132 is shorter, the overlapping level between the sub-images I1, I2, I3 having different visual angles is greater, such that image forming quality of the 3D image is decreased. However, in order to increase the focal length of the lens array 132 for improving the image forming quality of the 3D image, thickness of the optical element 130 is required to increase correspondingly, such that the 3D image display device 100 becomes thicker. The 3D image display device 100 of the prior art is not able to reduce the thickness of the optical element and improve the image forming quality of the 3D image at the same time.